1. Field Of The Invention
The invention pertains to the field of high frequency power supply generators, including among other things to power supplies for use with high frequency power supply generators.
2. Background of the Invention
High frequency power has a wide variety of applications in areas ranging from communication to industrial control equipment. Radio frequency power is a group of high frequency power generally having a frequency greater than thirty (30) kilohertz and power levels of up to 10 KW.
In operation a high frequency power supply generator utilizes AC mains power to supply power to a radio frequency amplifier, which is switched on and off according to a high rate drive signal. A device to which the radio frequency amplifier is coupled uses the high frequency power generated by the radio frequency amplifier. Applications utilizing high frequency power supply generators include power amplifiers for radio frequency communication, plasma generators for integrated circuit manufacture, circuit board etching apparatuses, physical vapor deposition chambers, chemical vapor deposition chambers, and devices for various other applications.
There are two known types of power supplies used to power radio frequency amplifiers in high frequency power supply generators. Referring to FIG. 1, a first known D.C. power supply for supplying power to high frequency power supply generators is shown. Step down transformer 5 reduces the 120-Volt, 208-volt rms., AC mains voltage to a level that can be utilized by the radio frequency amplifier 15. The reduced AC voltage is then rectified by rectifier 10 into a DC voltage that is used to supply power to radio frequency amplifier 15 that supplies a radio frequency signal to a load. Problems associated with the power supply depicted in FIG. 1 include the losses associated with the utilization of transformer 5. These losses include hysterisis losses, eddy current losses and magnetization losses. These losses generate large amounts of heat, which generally use a fan and a heat sink to cool the power supply. The addition of a fan and heat sink increases the bulk, weight and cost of the power supply. The large size of a power supply utilizing a cooling fan and heat sink adds to the drawbacks of using the power supply of FIG. 1. One of these drawbacks is that the high frequency power supply with the fan and heat sink is of a large size that makes it difficult to integrate the high frequency power supply into a small device that uses the high frequency power.
Referring to FIG. 2, a second known power supply utilized for radio frequency amplifiers is shown. The power supply includes a bridge rectifier 22 and a capacitor 24 for generating a DC voltage from the AC mains voltage. The DC voltage is input into a bridge of transistors 26 that is switched at a rate of 100 KHz at the primary side 28 of the transformer 30 so that the voltage at the secondary side, which includes a rectifier 32, is less than the primary side voltage. The voltage output 28 by the bridge of transistors 26 is a square wave. The advantage of the power supply depicted in FIG. 2 over that of FIG. 1 is that transformer 30 is smaller than transformer 5 because transformer 30 can operate at a higher frequency, this also means that less heat is generated by transformer 30 than transformer 5. A problem with the power supply depicted in FIG. 2 is that the addition of a bridge of transistors 26 add material costs to the power supply. Additionally, the bridge of transistors 26 adds losses. Further, the power supply of FIG. 2 while smaller than that of FIG. 1, is still of a large size so as to cause difficulties in integrating the power supply into devices that utilize high frequency power.
In the known power supplies of FIG. 1 and FIG. 2 the secondary side voltage is usually between 50 and 150 volts.
Referring to FIG. 3, a known high frequency power supply generator utilizes a power supply 50 that can be either of the power supplies depicted in FIG. 1 or FIG. 2. The power supply 50 provides power to the radio frequency amplifier 60, which produces the high frequency power that is filtered through a load network 70 and filter 80. As can be seen in FIG. 3, the ground 90 for each of the components is ground to the chassis that houses the high frequency power supply generator.
Problems associated with the prior art high frequency power supply generator depicted in FIG. 3, include its large size, high level of heat dissipation, and material cost due to the numerous components.
Therefore, it is desired to create a high frequency power supply generator that is highly reliable and inexpensive.
It is also desired to create a high frequency power supply generator that minimizes losses.
It is additionally desired to create a high frequency generator that minimizes the amount of heat generated.
It is further desired to create a high frequency power supply generator that is small in size to allow for easier integration into the overall system that utilizes the high frequency power supply generator.